DE1233516B - Process for machine arc deposition welding of metals with a consumable electrode - Google Patents

Description

Process for machine arc deposition welding of metals with consumable electrode In technology it is often necessary to use sensitive or highly stressed parts, especially those made of steel, from corrosive attack Protect media. There are two ways of doing this, namely roll cladding the sensitive workpiece surfaces with a corrosion-resistant material or the overlay welding of such a material, also weld cladding called. For manufacturing reasons, roll cladding is different for larger ones Shell wall thicknesses. Such parts are for example in the chemical industry and reactor pressure vessel. In many cases, build-up welding is therefore used. Since roll claddings often have major bonding defects, this alone also becomes For this reason, overlay welding is often preferred.

There are known sub-powder = deposition welding processes in which a low penetration and a smooth surface, preferably on curved containers, is to be achieved in that several linearly progressing weld beads in Distance from each other are welded and then the gap with coarse-grained Metal powder is filled, which with the same welding device and after the same procedure, d. H. with the same amperage and feed rate the welding electrode, is brought to melt (see U.S. Patent 3 022 413).

The object of the invention is to provide a method for machine arc deposition welding of metals with a consumable electrode to create a very low penetration (less than 5%, based on the application amount) and despite the low level of burn-in, a lack of fusion in the border area of two adjacent ones Largely avoids welding beads.

According to the invention this is achieved in that the arc in a manner known per se, a currentless additional wire is fed that with pendulum Welding head one application bead is placed on another without overlapping and that then the gusset between two application beads, preferably with the same welding head can be filled in without commuting.

By using the currentless additional wire, penetration be kept very low. In particular, by controlling the burn-off ratio between the additional wire and the wire electrode largely influences the penetration depth will. Despite the small penetration depth is due to the additional process step - the filling of the gusset with a linearly advancing weld bead - ensured, that in the border area of two weld beads, binding errors are largely avoided.

A further bead is advantageously used after the first application bead Application bead welded and are then alternately one gusset bead without Pendulums as well as an application bead welded with pendulums. This eliminates disturbances like when two weld beads are laid one next to the other by grooving of the additional wire can occur in the already fixed weld bead with Avoided security.

Serve to explain the method according to the invention in more detail Figs. 1 and 2.

F i g. 1 shows a welding device for carrying out the method according to the invention; F i g. 2 shows the welding in perspective several adjacent welding beads according to the invention.

In Fig. 1, an electrode guide is designated by 10, which is moved to and fro around the joint 20 with the aid of a cardiac curve 30. The setting of the welding electrode in the Y-direction, that is perpendicular to the workpiece, takes place via a corresponding rotation of the fork piece 19 on the pin 190, with a locking possibility, not shown, being provided. The pivoting of the welding electrode takes place, as already mentioned, via the cam disk 30, which actuates a lever system consisting of the tracer pin 29 pressed by the spring 27 and the contact roller 28 as well as the support lever 23 and the lever attachment 21. The amplitude of the pivoting movement is set by moving the articulated connection point 22 between the levers 23 and 21. Inside the electrode guide 10, the “hot” welding wire 8, from the end of which the arc burns against the workpiece, is guided and continuously pushed in from the magazine 12 by the transport rollers 11. The welding current from the direct current generator 3 is fed via a control device 2 to point 7 on electrode guide 10 and point 4 on the workpiece. A further electrode guide head 15 is attached to the electrode guide 10 via a side arm 18, which feeds a second welding wire - called cold wire, since no arc burns from it - via the rollers 16 from the second magazine 17 to the welding point. The movement of the welding electrode is controlled by the heart curve 30.

The amount of "cold" welding wire fed in is set in such a way that that it is approximately equal to or greater than the amount of "hot" welding wire. The cold welding wire does not need to be thicker than the hot one. Much more can produce a larger volume from thinner than from thicker cold wire in the same time be melted in the weld pool as the surface of a wire to be based on Weight or volume, as the radius becomes smaller, it becomes larger and therefore a better one Allows heat transfer.

Instead of a thin wire, a ribbon can of course also be used or a foil can be used.

The toughness of the weld metal causes it to run ahead and possibly also lateral overhanging of the caterpillar reduced or completely prevented. The weld between only slightly overheated tough weld metal and likewise essentially only superficially brought to melting temperature via this weld metal The base material causes only a very small penetration depth of less than 511 / o of the order amount and from this, in turn, the expected for use and the further processing of the workpieces with advantageous technical properties.

The lamellas are almost perpendicular to the workpiece surface. This structure of the weld bead results in a very even and smooth surface, which has a significantly lower roughness compared to a machined one, which themselves ; can only have a beneficial effect in terms of corrosion behavior. The costs A subsequent surface treatment can also be saved.

When it comes to overlay welding of larger areas, what Usually, it must, since the pendulum amplitude is not made arbitrarily large can be set, weld bead to weld bead.

For the case of stringing welding beads, the result is when applying the new weld bead to the old weld bead, an increase in cross-section of the base material and thus other warming conditions. To avoid For example, there could be defects in the joint between the two weld beads under the joint the speed of the welding electrode can be controlled so that they at this The impact point lingers a little longer. In this way it becomes possible in the overlapping area To avoid blemishes with certainty and at the same time a smooth transition to achieve, additionally by stopping or slowing down the cold wire feed at this point, where less welding material is needed anyway, a larger one Amount of heat is supplied without a deeper penetration into the base material takes place into it.

Another way that leads to very good results, i. i.e., too extensive With the invention, there is no lack of binding in the border area of two weld beads trodden. This route is shown in FIG. 2 shown. The weld beads are with normal speed control arranged side by side and without overlap the gusset-shaped groove remaining between the two by any welding process filled in, but advantageously with the same welding device, but below Omission of pendulum motion and cold wire. The appropriate sequence of welding is in Fig. 2 represented by arrows. First caterpillar I, then caterpillar II, then gusset seam Ia, then bead III, then gusset seam IIa etc. welded, it is So, so to speak, a pilgrim step technique applied. This method has advantages in three ways.

If the welding beads overlap, there is a risk of that if the cold wire speed is too high, the cold wire enters the fixed neighboring bead, when the pendulum reaches the point of overlap, it spikes and thus irregularities and causes disturbances. This is not necessary when the welding beads are placed next to each other Danger, and the cold wire speed can be increased significantly. That is when working out the welding data combination for penetrations below 5% in some Cases essential.

The second advantage is that overlap binding errors are easier and can be avoided completely safely. Finally, especially in the case of heat cracks sensitive Application materials avoid cracks due to the long shrinkage paths of the broad caterpillars occasionally occur at the overlapping areas.

The caterpillars can either border one another exactly or with Gaps are placed or only overlap to a small extent.

The welding of the bead and the gusset filling is expedient in the pilgrimage method.

Claims (2)

Claims: 1. A method for automatic arc build-up welding of metals with a consumable electrode, characterized in that a currentless additional wire is fed to the arc in a manner known per se others are placed and that the gussets (Ia, Ha) between each two application beads are filled with preferably the same welding head without oscillation. 2. The method according to claim 1, characterized in that following the first application bead (I), a further application bead (1I) is welded and then alternately a double bead (I a) without pendulum and an application bead (III) are welded with pendulums. Documents considered: German Patent No. 954 817; USA: Patent Nos. 2,909,649, 3,022,413; EOPaton, Automatic Arc Welding, Halle (Saale), 1958, p. 301; W. Schatz, Die Unterpulverschweißung, Eisenberg / Pfalz, 1962, p. 166, 170 to 172; WM C onn, Die Technische Physik der Lichtbogenschweißung, Berlin et al., 1959, pp. 112/113, 333/334; F. Erdmann-Jesnitzer, Material and Welding, Vol. I, Berlin, 1951, p. 473; Schimpke-Horn, Practical Manual of Entire Welding Technology, Vol. II, 5th Edition, Berlin et al., 1950, p. 293.